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Evaluatig Noise Reduction and Insertion Loss
Posted Jul 23, 2012, 2:13 a.m. EDT Acoustics & Vibrations Version 4.1 0 Replies
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I'm trying to evaluate Noise Reduction and Insertion Loss for open-end tube onto acoustics fields.
fortunately, I did calcalate Transmission Loss successfully. Because setting the outlet tube boundary contion is pretty simple. I assume anechoic termination at the end of tube, so I put the impedance Z_0 likes rho*c(speed of sound in air).
But I cant use that impedance when I calculate Noise Reduction and Insertion Loss, because these cases are NOT anechoic terminatio. So I put the equation likes..
Z_0 = rho*c*(0.25*(k*r0)^2+j*0.6*k*r0) (subject to k*r0<0.5)
This equation came from Levine and Schwingers' study(1947).
I tryed to calculatre this problem so many times whit COMSOL, but I cannot reach satisfy results.
That contains too many negative values.I expect your briliant advices.
Best Regards
Hello Kee Seung Oh
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